statistics & spss review
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Statistics & SPSS Review. Fall 2009. Types of Measures / Variables. Nominal / categorical Gender, major, blood type, eye color Ordinal Rank-order of favorite films; Likert scales? Interval / scale Time, money, age, GPA. Main Analysis Techniques. Main Analysis Techniques. - PowerPoint PPT PresentationTRANSCRIPT
Statistics & SPSS Review
Fall 2009
Types of Measures / Variables
• Nominal / categorical– Gender, major, blood type, eye color
• Ordinal– Rank-order of favorite films; Likert scales?
• Interval / scale– Time, money, age, GPA
Variable Type Example Commonly-used Statistical
Method
Nominal by Nominal blood type by gender
Chi-square
Scale by Nominal GPA by gender
GPA by major
t-test
Analysis of Variance
Scale by Scale weight by heightGPA by SAT
RegressionCorrelation
Main Analysis Techniques
Variable Type Example Commonly-used Statistical
Method
Nominal by Nominal blood type by gender
Chi-square
Scale by Nominal GPA by gender
GPA by major
t-test
Analysis of Variance
Scale by Scale weight by heightGPA by SAT
RegressionCorrelation
Main Analysis Techniques
SPSS Cross –tab with Chi-Squarevictim gender * probation or jail Crosstabulation
3 21 2412.5% 87.5% 100.0%
9 15 2437.5% 62.5% 100.0%
12 36 4825.0% 75.0% 100.0%
Count% within victim genderCount% within victim genderCount% within victim gender
female
male
victim gender
Total
probation jailprobation or jail
Total
Chi-Square Tests
4.000b 1 .0462.778 1 .0964.144 1 .042
.093 .047
3.917 1 .048
48
Pearson Chi-SquareContinuity Correctiona
Likelihood RatioFisher's Exact TestLinear-by-LinearAssociationN of Valid Cases
Value dfAsymp. Sig.
(2-sided)Exact Sig.(2-sided)
Exact Sig.(1-sided)
Computed only for a 2x2 tablea.
0 cells (.0%) have expected count less than 5. The minimum expected count is 6.00.
b.
SPSS Cross –tab with Chi-Squarevictim gender * probation or jail Crosstabulation
3 21 2412.5% 87.5% 100.0%
9 15 2437.5% 62.5% 100.0%
12 36 4825.0% 75.0% 100.0%
Count% within victim genderCount% within victim genderCount% within victim gender
female
male
victim gender
Total
probation jailprobation or jail
Total
Chi-Square Tests
4.000b 1 .0462.778 1 .0964.144 1 .042
.093 .047
3.917 1 .048
48
Pearson Chi-SquareContinuity Correctiona
Likelihood RatioFisher's Exact TestLinear-by-LinearAssociationN of Valid Cases
Value dfAsymp. Sig.
(2-sided)Exact Sig.(2-sided)
Exact Sig.(1-sided)
Computed only for a 2x2 tablea.
0 cells (.0%) have expected count less than 5. The minimum expected count is 6.00.
b.
p < .05
Variable Type Example Commonly-used Statistical
Method
Nominal by Nominal blood type by gender
Chi-square
Scale by Nominal GPA by gender
GPA by major
t-test
Analysis of Variance
Scale by Scale weight by heightGPA by SAT
RegressionCorrelation
Main Analysis Techniques
SPSS t-test Output
Group Statistics
24 16.04 12.723 2.59724 6.00 9.227 1.883
victim genderfemalemale
lengthofsentave11N Mean Std. Deviation
Std. ErrorMean
Independent Samples Test
.824 .369 3.130 46 .003 10.042 3.208 3.584 16.499
3.130 41.951 .003 10.042 3.208 3.567 16.516
Equal variancesassumedEqual variancesnot assumed
lengthofsentave11F Sig.
Levene's Test forEquality of Variances
t df Sig. (2-tailed)Mean
DifferenceStd. ErrorDifference Lower Upper
95% ConfidenceInterval of the
Difference
t-test for Equality of Means
SPSS t-test Output
Group Statistics
24 16.04 12.723 2.59724 6.00 9.227 1.883
victim genderfemalemale
lengthofsentave11N Mean Std. Deviation
Std. ErrorMean
Independent Samples Test
.824 .369 3.130 46 .003 10.042 3.208 3.584 16.499
3.130 41.951 .003 10.042 3.208 3.567 16.516
Equal variancesassumedEqual variancesnot assumed
lengthofsentave11F Sig.
Levene's Test forEquality of Variances
t df Sig. (2-tailed)Mean
DifferenceStd. ErrorDifference Lower Upper
95% ConfidenceInterval of the
Difference
t-test for Equality of Means
1. Read means
2. Read Levene’s Test 3. Read p value
Variable Type Example Commonly-used Statistical Method
Nominal by Nominal blood type by gender
Chi-square
Scale by Nominal GPA by gender
GPA by major
t-test
Analysis of Variance
Scale by Scale weight by heightGPA by SAT
RegressionCorrelation
Analysis of Variance
SPSS ANOVA outputDescriptives
lengthofsentave11
19 14.26 15.183 3.483 6.94 21.58 0 6014 7.43 8.474 2.265 2.54 12.32 0 2415 10.27 10.067 2.599 4.69 15.84 0 3648 11.02 12.109 1.748 7.50 14.54 0 60
natural sciencesocial sciencearts and humanitiesTotal
N Mean Std. Deviation Std. Error Lower Bound Upper Bound
95% Confidence Interval forMean
Minimum Maximum
ANOVA
lengthofsentave11
388.933 2 194.467 1.346 .2716502.046 45 144.4906890.979 47
Between GroupsWithin GroupsTotal
Sum ofSquares df Mean Square F Sig.
SPSS ANOVA outputDescriptives
lengthofsentave11
19 14.26 15.183 3.483 6.94 21.58 0 6014 7.43 8.474 2.265 2.54 12.32 0 2415 10.27 10.067 2.599 4.69 15.84 0 3648 11.02 12.109 1.748 7.50 14.54 0 60
natural sciencesocial sciencearts and humanitiesTotal
N Mean Std. Deviation Std. Error Lower Bound Upper Bound
95% Confidence Interval forMean
Minimum Maximum
ANOVA
lengthofsentave11
388.933 2 194.467 1.346 .2716502.046 45 144.4906890.979 47
Between GroupsWithin GroupsTotal
Sum ofSquares df Mean Square F Sig.
p value
Variables & Statistical TestsVariable Type Example Common Stat
MethodNominal by nominal
Blood type by gender
Chi-square
Scale by nominal GPA by genderGPA by major
T-testAnalysis of Variance
Scale by scale Weight by heightGPA by SAT
RegressionCorrelation
Variance
x i - Mean )2
Variance = s2 = ----------------------- N
Standard Deviation = s = variance
Regression line
W = 3.3 H - 73
Scatterplot: Sentence by G.P.A.
Regression Coefficients
Coefficientsa
17.853 12.097 1.476 .155-3.534 3.368 -.223 -1.049 .306
(Constant)grade point average
Model1
B Std. Error
UnstandardizedCoefficients
Beta
StandardizedCoefficients
t Sig.
Dependent Variable: jail sentencea.
Sentence = -3.5 G.P.A. + 18
Correlation
Correlation: Sentence & G.P.A.
Correlations
1 -.223. .306
23 23-.223 1.306 .
23 24
Pearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)N
grade point average
jail sentence
grade pointaverage jail sentence
Correlation: Sentence & G.P.A.
Correlations
1 -.223. .306
23 23-.223 1.306 .
23 24
Pearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)N
grade point average
jail sentence
grade pointaverage jail sentence
p value
Interpreting r as r2
r = -.22 r2 = .05
G.P.A. “explains” 5% of variance in SENTENCE length
Correlation